The Disinfection of Streets and Sewers.—How some of the worthless by-products of chemical works might be turned to good account in disinfecting the streets of our American cities, is shown by Mr. H. G. Debrunner, in the Philadelphia Chemist and Druggist. He is led, by the results of experiment, to believe that street-mud and the sewer-water containing the same are the main factors in the distribution of contagious disease. This matter could be effectually disinfected, and that without extraordinary expense, by treating it with certain waste products, such as the mother-liquors of copperas aud alum. Many a factory would be glad to get rid of this refuse, and would give it away for nothing. With these disinfectants, diluted with water to the desired strength, the streets should be sprinkled; most of the waste substances are so powerful that they may be greatly diluted without losing their efficacy. In street-dust, the author has found, besides the usual inorganic bodies, a number of organic substances—as, for instance, glutinous matter coming from abrasions of the hoofs of cattle. This matter varies in quantity from one-half to five per cent., and in some dust taken from roads leading to stock-yards it has been found in the proportion of as much as fifteen per cent. It decomposes readily, especially in the presence of water, and microscopic examinations of aqueous extracts of the mud from such localities show living beings of the lowest classes of the vegetable and animal kingdom—algæ, fungi, and various forms of infusoria.

The Harpy Eagle.—The harpy eagle (Harpyia destructor), of which a sprightly description is given by Dr. Felix L. Oswald in the American Naturalist, has its native home in the forests of Southern Mexico. Its common English and its systematic name, as well as its Spanish title, Aquila real (king-eagle), and its old Mexican name of "winged wolf," fitly characterize the rapacity of this bird. It has a square, strong head, armed with a powerful bill that can without any special effort crush a man's finger-bones. Its broad, compact wings are moved by shoulder-muscles of enormous strength; and its stout legs, feathered to below the tarsi, terminate in claws of such extraordinary power and sharpness that they leave their marks on the tough leather of a Mexican saddle, like the bite of a wild-cat. Its plumage is so elastic, so compact, and so firmly imbricated, that buckshot, striking on the wings or the breast of the bird at a certain angle, glance off, or fail to penetrate to vital parts. The fully-grown hen measures about three feet from its crest to the base of the tail, and from six to seven feet from tip to tip of the outstretched wings. The male is somewhat smaller, but the strength of the bird in proportion to its size is altogether abnormal. A tame old harpy eagle once engaged in mortal-combat with a big shepherd-dog, and was only vanquished by a second dog that came to the assistance of his fellow. In a fight of ten minutes the first dog had received a deep gash in his throat (from which he soon bled to death), lost one of his eyes, and the bones of his skull and breast had been laid open in numerous places. In a fight between a harpy eagle and a Mexican lynx which had been crippled by a shot through its haunches, but was otherwise in good fighting condition, the bird was torn to pieces, but the lynx did not survive him many minutes, having been literally flayed from its shoulders to the tip of the nose. The following narrative shows the bird's tenacity of life: A Mexican miner, before daybreak one morning, in the mountains near Orizaba, surprised a pair of harpies, and with a cudgel knocked down one of them, which flew directly at his head. The miner now dispatched the bird as he thought, with a few well aimed whacks, and, shouldering his game, resumed his journey toward the valley. Half-way down the mountain-side he reached a steep cliff, and shifted his burden to his left shoulder, to use his right arm to better advantage. But at the most critical moment of the dangerous descent he suddenly felt the claws of the eagle at his neck, and, in order to save himself, had to drop his stick, which fell down the cliffs and into the bed of a mountain-torrent. Holding on to the bird with one hand, he managed to reach the foot of the precipice, where he seized the struggling-captive by the legs, and, swinging it up, dashed its head against a rock, till its convulsions had ceased entirely. His arrival in the village, with the story of his adventure, created quite a sensation; but, when the bird was deposited on the ground to be examined at leisure, it revived for the third time, struck its claws through the hand of its captor, struggled to its feet, and would have escaped after all, if the enraged miner had not flung himself upon it, seized a stone and hammered its head to a jelly.

Muslin Glass.—The mode of producing so-called "muslin glass" is as follows: After carefully cleaning the surface of a plate of glass, a layer of verifiable color is laid over it, the vehicle being gum-water, and care being taken to have the pigment evenly applied. The glass is then submitted to a gentle heat until the water has evaporated, when a stencil of the desired pattern is laid over the surface, and with a stiff brush the pigment is removed from the parts which are to be transparent. The glass is next inclosed in a frame, and above it is extended a piece of tulle or, if desired, embroidered lace, the embroidery in the latter case being so disposed as to harmonize with the ground-pattern previously made. The whole is then hermetically closed in a box which contains in its lower portion a reservoir holding a certain quantity of dry color in the form of impalpable powder. This by an air-blast is blown evenly upon the glass and adheres to the latter wherever the surface is not protected by the threads of lace. In this way the pattern of the latter is defined. In order to fix the powder, the sheets of glass are placed in a steam-chamber where the steam moistens the gum and causes the powder to adhere. The color is then burned in a special furnace.

Variability of the Nebulæ.—In a lecture recently delivered at Paris, under the auspices of the Scientific Association of France, the eminent Swiss astronomer Wolf gave an account of recent researches on the "variability of the nebulæ." His conclusions, as stated in La Nature, are: that some of the nebulae are certainly in a state of relative motion—at least one double nebula being known to astronomers, the component parts of which revolve about each other; that in all probability some of the nebulæ are waning and disappearing—as instances of this he cites three nebulæ in the constellation of Taurus; that possibly some of the nebulæ are undergoing a change of form; the spiral nebula in Canes Venatici appears to afford an illustration of this fact. As for the distances of the nebulæ, they cannot yet be determined, but there are grounds for believing that many of them are not more remote from us than the fixed stars.

Copying Designs by Photography.—A new process of making photographic copies of machinery, drawings, plans, maps, etc., in blue lines on a white ground, has been invented by H. Pellet, a chemist of Paris. This process (says La Nature) is based on the peculiar property possessed by perchloride of iron, whereby it is converted into protochloride by exposure to light. The protochloride is not affected by contact with prussiate-of-potash solution, but the perchloride at once becomes blue. M. Pellet sensitizes a sheet of paper by dipping it in a bath consisting of water 100 parts, perchloride of iron 10 parts, oxalic or some other vegetal acid 5 parts. In case the paper was not sufficiently sized, gelatine, isinglass, dextrine, or some such substance, would have to be added to this solution. The paper so treated—M. Pellet calls it now cyanofer-paper—is dried in the dark, and may then be kept for a length of time. It is very sensitive to light. To make a copy of a drawing made on transparent paper, the drawing is spread over a dry sheet of the cyanofer, a plate of glass laid over all, and the whole exposed to the light. In summer, with exposure to the full sunlight, it takes from fifteen to thirty seconds to decompose so much of the perchloride of iron as is not protected by the lines of the drawing. In winter, an exposure of forty to seventy seconds is necessary. In the shade, in clear weather, the exposure varies from two to six minutes, and in cloudy or rainy weather, from fifteen to forty minutes. The electric light may be used instead of sunlight, the time of exposure varying according to the intensity of the light and the distance. After exposure, the paper is dipped in a bath of prussiate of potash (15 to 18 per 100 parts of water), and it at once assumes a blue color wherever the perchloride is unaltered, all the rest of the surface remaining white. The image is then freely washed in water, and passed through a bath of chlorhydic acid (8 to 10 parts to 100 of water), which removes the protoxide of iron salt; it is then washed again in water, and finally dried. The drawing then appears in blue lines on the pure white ground of the paper.

The Chinese Loess or Loam Deposits.—The origin of the "loess" deposits of China has long been a perplexing problem for geologists. This deposit is spread almost continuously over an area as large as the German Empire, besides existing in detached areas of nearly half that extent. Usually, the loess is several hundred feet in thickness, and in some places as much as 1,500 or even 2,000 feet. It is an earthy substance, of a brownish-yellow color, friable, chiefly consisting of argillaceous materials, with a small proportion of carbonate of lime; it has also mixed with it more or less of fine sand, the grains of which are very angular. The Baron von Richthofen, in his work on "China," the first volume of which has appeared, offers the most satisfactory theory yet presented of the origin of this loess. A very clear statement, both of the problem itself and of Von Richthofen's solution of it, is given by Prof. J. D. Whitney, in the American Naturalist, who states that the first geologist to notice and describe these remarkable deposits was Prof. Pumpelly. According to him, the loess of China is a lacustrine formation, each of the basins in which it occurs having been once the bed of a lake. But the absence of stratification and of fresh-water shells, and the presence of the bones of land-animals, appear to be utterly incompatible with this theory. Besides, the loess indicates by its structure the growth on its surface of an abundant vegetation. But a greater difficulty still stands in the way of the theory of a lacustrine origin—namely, the fact that everywhere the loess plainly shows itself to be a deposit which was not laid down till after the surface of the country had assumed its present configuration. Hence Richthofen unhesitatingly declares himself in favor of a subaërial origin of the loess. Wind and rain are, according to him, the agencies which produced these deposits. In the first place, he assumes the district of the loess to have been once destitute of outward drainage, and to have, in fact, consisted of a number of closed basins, such as are still found in the adjacent region, to the west, in Central Asia. These closed basins were prairies, and the loess is the collective residue of innumerable generations of herbaceous plants. It is the inorganic residuum which has accumulated during an immense lapse of time, as the result of the decay of a vigorous prairie-growth, ever renewing itself on the surface of the slowly-accumulating deposit. But how is the increase of the deposit provided for by the theory? Unless there be some source supplying material from without, there can evidently be no gain in thickness, however many generations of plants succeed each other. The necessary addition of mineral matters Richthofen considers to have been brought into these basins by two agencies, the rain and the wind, and the latter especially plays an important part in his theory. Each basin being surrounded by a rim of rocks, constantly undergoing decomposition, the particles thus set free were either swept down the mountain-sides toward the central area by rain, or blown thither by air-currents, and, once entangled among the vegetation, could not be caried farther.

The Pennsylvania Oil-Regions.—The oil-regions of Pennsylvania are, in an article by M. C. A. Ashburner, in the Journal of the Franklin Institute, divided into three districts, the southwestern, the western, and the northern, the southwestern lying south of the Ohio and west of the Monongahela, the western occupying the water-basin of the Alleghany, between Pittsburg on the south and the Philadelphia & Erie Railroad on the north, and the northern district extending north from the line of the same railroad. In the first of these districts the petroleum comes from the highest rocks, and in the third from the lowest, while in the second it comes from the rocks intermediate between the two. The "oil-sand group" of the southwestern district is composed of three sandstone members, separated by intervals containing coal-seams, slate, and shale; but the second of these three members—the Mahoning sandstone—is the principal repository of petroleum in the southwestern district. The "oil-sands" of the western district are also three in number. The first sand of this group yields a heavy lubricating oil, 30° to 35° gravity; the second, an oil about 40° gravity; the third, a light oil, 45° to 50° gravity. This third sand is the most productive, and supplies most of the oil of commerce. The "Warren oil-sand" of the northern district is very irregular in character, and the oil is found at horizons varying from 600 to 800 feet below the "third sand" of the preceding group, whose oil it, moreover, resembles. But at a depth of about 300 feet below the Warren horizon, and in the same northern district, is the Bradford oil-belt of McKean County, Pennsylvania, and Cattaraugus County, New York, the surest and safest oil-territory in all the oil-regions. The oil of the Bradford belt is of the same gravity as "third-sand oil."

The Ancient Beaches of Great Salt Lake.—The mountains round about Great Salt Lake bear plain evidences of the existence at some early period of a much larger lake in the same locality. The sides of these mountains rise, as it were by steps, to the height of 1,000 feet above the surface of the present lake, these steps marking the successive levels of the lake as it shrunk from its primeval dimensions—345 miles long, 135 miles broad—to the size it now possesses. Mr. G. K. Gilbert, of Powell's Survey, has made a very thorough study of these ancient beaches, and publishes an article on the subject in a recent number of the American Journal of Science. This ancient lake has received from geologists the name of Lake Bonneville, and the great problem was, to discover the outlet through which its waters were drained away. To this end it was necessary to find a point where the Bonneville shore-line was interrupted by a pass of which the floor was lower than the shore-line, and which led to a valley not marked by a continuation of the shore-line. These conditions are satisfied at Red Rock Pass, and, in addition, there is a continuous descent from the pass to the Pacific Ocean. All about Cache Valley the Bonneville shore-line has been traced, and it is well marked within a half-mile of the pass. The floor of the pass at the divide is 340 feet below the level of the shore-line, and its form is that of a river-channel. The gentle alluvial slopes from the mountains at the east and west, which appear once to have united at the pass, are divided for several miles by a steep-sided, flat-bottomed, trench-like passage, 1,000 feet broad, and descending northward from the divide. At the divide Marsh Creek enters the old channel from the east, and, turning northward, runs through Marsh Valley to the Portneuf River, a tributary of the Columbia. In Marsh Valley the eye seeks in vain for the familiar shore-lines of the Salt Lake Basin, and the conclusion is irresistible that here the ancient lake outflowed. On the sides of the mountains, from the highest shore-line, known as the 'Bonneville Beach,' down to the level of the modern lake, there is a continuous series of wave-wrought terraces recording the slow recession of the water. As many as twenty-five have been counted on a single slope. Some are strongly marked and others faintly, and some that are conspicuous at one point fail to appear at other points; but there is one that under all circumstances asserts its supremacy and clearly marks the longest lingering of the water—the 'Provo Beach,' which runs about 365 feet below the Bonneville Beach. When the discharge of the lake began, its level was that recorded by the Bonneville Beach. The outflowing stream crossed the unconsolidated gravels that overlay the limestone at Red Rock, and cut them away rapidly. The lake-surface was lowered with comparative rapidity until the limestone was exposed, and thenceforward the process was exceedingly slow. For a long period the water was held at nearly the same level, and the Provo Beach was produced. Then came the drying of the climate, and the outflow ceased; and slowly the lake has since shrunk to its present size.

Discolored Sea-Water.—While engaged in a survey of the Gulf of California—the Mar Vermijo, or Vermilion Sea of the early Spanish navigators—Surgeon T. H. Streets, of the navy, examined some of the water in order to ascertain the cause of the peculiar coloration. This red color occurs in patches, and does not extend to the whole area of the gulf. Having reached one of these patches, Dr. Streets had a bucket of the water taken on board the steamer, but it was found to be perfectly transparent. But, on sinking the bucket half a fathom or more below the surface, water was brought up which contained the coloring-matter in abundance. "When first drawn up," writes Dr. Streets in the American Naturalist, "and viewed in a glass vessel, by the unaided eye, the water had a faint reddish tinge. When allowed to stand for half an hour, the coloring-matter settled to the bottom of the vessel as a greenish-yellow precipitate; and when some of this was taken up by a pipette and examined under the microscope, it was seen to be composed of minute roundish bodies," the remains of ciliate infusoria, as they were proved to be after much laborious investigation. Under the microscope certain small objects were seen repeatedly darting across the field of vision, when the water was placed fresh upon the glass slide, but they disappeared as quickly as they came, and for a long time it was impossible to tell what had become of them. But at length one of the little bodies stopped directly in the centre of the field of vision and commenced a rapid rotatory movement, which presently ceased, and the animal was quiescent for a second or two; then rupture occurred, the molecular contents oozed out, and the transparent envelope of the organism became invisible. The observation was again and again repeated. The author quotes from Darwin's "Naturalist's Voyage around the World" a passage in which a similar observation is recorded with regard to certain patches of discolored water encountered off the coast of Peru.

Grape-Culture.—To determine the influence of girdling grape-vines on the growth and composition of the grapes, Prof. C. A. Goessmann last year made a series of experiments which are described in the "Proceedings of the American Chemical Society." He had a number of vines girdled during the first week of August, about the time when in the berries of the Concord grape the free acid had attained its highest development, and the grape-sugar was beginning slowly to increase. Entire vines as well as large branches served for the trial. Two incisions from one-eighth to one-quarter of an inch apart were made through the bark and the cambium layer, and the mass between these cuts down to the wood carefully removed. A marked difference in the degree of growth was soon perceived, which persisted during the entire season, until the grapes on the girdled branches had just become ripe. The tests made at this point with both the grapes of the girdled and of the ungirdled branches, grown on the same vine, showed a remarkable difference in the quality of the entire grape and in its relative degree of development. In some instances the girdled branches were two to three weeks in advance of the others. At the close of the season the girdled vines did not show the slightest difference from the ungirdled ones, the place where the bark had been removed being grown over.

Disadvantages of the Health-Lift.—The use of the "health-lift," so called, was under discussion recently in the Philadelphia County Medical Society, and Dr. Benjamin Lee read a paper on the subject, in which he condemned the practice as being neither rational, scientific, nor safe. The paper has been published in the Medical and Surgical Reporter, from which journal we select a few of the objections brought by Dr. Lee against the "health-lift." Exercise, according to Dr. Lee, in order to produce beneficial effects, must extend over a considerable length of time each day, and must be so moderate in its character that such continuance shall not render it exhausting. But it is claimed as the distinctive merit of the "health-lift" that it accomplishes a maximum of exercise in a minimum of time: "Ten minutes a day only is required." That is, "ten minutes a day" to fill the lungs up to their utmost capacity with pure, fresh, oxygenated air, so that every cell may do its duty. "Ten minutes a day" to set in full activity the thousand ducts of the sweat-glands, and to carry off noxious matters out of the blood; to recreate the weary brain-cells; to provoke absorption of the effete materials lying outside of the vessels throughout all the vessels of the body. In the next place, the first requirement of rational exercise is to call into play as far as possible all the muscles; and the second is, that it should be so varied as to afford at the same time pleasurable mental excitement or occupation. In both of these points the theory of the "health-lift" is faulty. It calls into action almost exclusively the extensor muscles of the lower extremities, and the erection of the spine with the associate dorsal groups. As far as the upper extremities are concerned, the only muscles called into activity are the flexors of the fingers; those of the arm and shoulder are simply put on the stretch, an operation which, without corresponding contraction, weakens rather than strengthens muscular fibre. At the same time, the ligaments of the joints are violently stretched, which must tend to diminish the completeness of the apposition of the joint-surfaces, and thus diminish precision and rapidity of motion. As regards variety and occupation for the mind, the "health-lift" confessedly possesses no such quality. Finally, the "health-lift" is not a safe mode of exercise. It tends to produce apoplexy, rupture of blood-vessels, hernia, and other serious evils. The author concludes with these words: "Concentrated exercise is as unsatisfying to the muscle as is concentrated nourishment to the stomach. The latter demands bulk in its contents, the former a certain duration in its period of activity."